The present invention relates to a new and improved apparatus for automatically inserting terminated wire leads into terminal-receiving cavities of a multi-circuit connector to form a wire harness. More particularly, it relates to a new and improved insertion apparatus including a lead insertion jaw assembly which does not rely on the column strength of the wire lead during insertion. The lead insertion jaw assembly may be used with an improved terminal guide assembly and an X-Y-Z programmable housing indexing module to provide a fully automated crimped wire harness fabrication machine capable of randomly inserting any gauge wire lead into the housing cavities of a multi-circuit connector in any order.
Many different kinds of wire harnesses are used for electrically interconnecting various electrical components to each other in an electronic device, component, or system. The wire harnesses typically include a plurality of insulated conductors in the form of discrete wire or cable and a plurality of electrical connectors provided at various positions along the conductor segments.
As is well known, crimp terminated leads can be inserted into a multi-circuit connector housing to provide an organized wire harness for use in interconnecting two or more electrical components. In accordance with crimp technology, the insulated conductors are stripped, typically at an end portion or at various positions along their length, to provide exposed conductor portions to which crimp terminals may be mechanically and electrically attached. The stripping and crimping operations required to provide electrically reliable crimp harnesses have become disadvantageously time consuming and expensive with the advent of insulation displacement technology.
In accordance with insulation displacement methods of wire termination, insulation displacement terminals are provided with wire receiving slots which are designed to cut through the outer insulation of the wire to make intimate gripping mechanical and electrical contact with the core conductor of the wire. Insulation displacement terminals do not require insulated wires to undergo preparatory stripping or crimping steps. Instead, the wire may simply be driven laterally of its axis into the insulation cutting slot provided in the metallic terminal.
Insulation displacement terminations are generally thought to be easier and less expensive to make and they are readily adapted to single step termination, as well as, mass termination. Customer acceptance of insulation displacement contact reliability has been achieved in some industries, such as, telecommunications and computer and peripheral equipment markets. An explosion in the development of automated tooling for use in fully automated manufacture of increasingly complex insulation displacement type wire harnesses has rapidly followed. Automatic insulation displacement wire harness fabricators capable of automatically terminating the same wire segments to dissimilar connectors, or dissimilar wire segments to a plurality of connectors, including complex cross over wire harnesses, are now known and commercially available.
Acceptance of insulation displacement termination technology for some industries, has been very difficult to achieve, particularly for those industries, such as automotive and aircraft manufacturing, wherein wire harnesses must be capable of reliably operating under high current conditions, as well as, in high vibration environments. These manufacturers have been reluctant to believe that insulation displacement contacts are reliable for their particular end-use environments. These industries still rely upon crimp termination technology to provide the secure mechanical and electrical engagement needed in high current and high vibration applications.
Accordingly, automated tooling designers and manufacturers are turning their attention to the development of new and improved fully automated crimp wire harness fabricators, for their customers who depend on crimp technology. Fully automated methods will provide these customers with the same increased production and lower installed costs, heretofore enjoyed by the insulation displacement customers.
Automated equipment and methods for fabricating crimp wire harnesses are presently known. In U.S. Pat. No. 4,308,659, for example, an automated block loading apparatus is described. The block loading apparatus includes means for conveying a plurality of terminated leads laterally their axes to a lead pick-up station. A connector housing including a plurality of terminal-receiving cavities is mounted for vertical movement in a stationary housing guide spaced from the conveyed wire leads. The apparatus described in this patent utilizes feed wheels which move into contact with a terminated wire lead and rotate in opposite directions to drive the lead through a guide tunnel into a cavity in the connector housing. The guide tunnel closely accommodates the wire during insertion. The apparatus loads a connector housing including a plurality of columns and rows of terminal receiving cavities by inserting one terminated lead at a time into one row of cavities and thereafter downwardly indexes the housing to present the next row of cavities for lead insertion. The apparatus is limited in its usefulness for preparing more complicated crimp wire harnesses because it requires that the leads be inserted one channel at a time, one row at a time, in a highly ordered manner. In addition, although the forward portion of wire lead is surrounded in a channel guide during insertion, the insertion mechanism relies on drive wheels which push the wire into the housing. This method of pushing a terminated lead into the connector housing relies upon the column strength of the wire.
Terminated wire leads adapted for press-in engagement with the terminal-receiving cavities of a connector frequently include a resilient locking tang or lance struck out from the terminal side wall or other projecting structure adapted to engage a latch recess or an inner surface of the cavity. These projecting features serve to lock the mating portions of a terminal in a proper forward position with respect to the mating face of the connector housing. The lances or other projections prevent rearward pull-out of the terminal and lead from the housing. The lance on the terminal must be deflected inwardly to permit the terminal to be slideably inserted into the housing cavity. As a result, there is a resistance to insertion including a locking tang deflection component, as well as, a sliding frictional component which must be overcome to successfully fully insert the terminated lead into the connector housing.
In some modern applications, vibration resistant crimped wire harnesses employing very fine gauge insulated wires are required. These finer-gauged leads do not possess sufficient axial rigidity, or column strength, to overcome the insertion forces required to force the terminal into a housing cavity. Accordingly, when finer gauged leads are gripped along their wire segment and driven toward the housing in an effort to insert the leads, the wires are not strong enough to overcome the insertion resistance so that they buckle and bunch against the rear end of the terminal, or the terminal is deflected out of alignment with the target cavity. Even with the aligning tunnel guide described in the above-mentioned '659 patent, an unsuccessful insertion will result if a finer gauge wire lead is employed with the apparatus because the drive mechanism relies on the column strength of the wire during terminal insertion.
Another automated apparatus for inserting terminated leads into a housing cavity is described in U.S. Pat. No. 4,607,430. This patent describes a terminal insertion module for a robot end-effector which positions pin-terminated crimped leads into a connector housing. The pin is clamped in a fixture and the wire is drawn tight by a rearward set of wire feed jaws. A cylindrical clamp with jaws at its opposed ends is closed about the tightened wire segment. An inner set of independently actuable jaws are provided within the cylinder member. The outer jaws at one end of the cylinder are clamped onto the back of the pin terminal and the rear wire tightening jaws are released. The cylindrical jaw assembly is moved toward the housing to insert the forward section of the pin terminal into a terminal receiving cavity. Thereafter, in accordance with this patent, the outer jaws are opened and the inner jaws firmly gripping the wire column are moved towards the connector housing to push the partly-inserted pin terminals to a fully inserted position in the connector housing. The apparatus and method described in this patent also rely on the column strength of the wire to achieve insertion which renders the apparatus unsuitable for use in finer gauge wire harness fabrication.
In U.S. Pat. No. 4,598,469, another apparatus and method for inserting terminated leads in a connector is described. In a socalled double pinch-push contact insertion method, two pairs of independently actuated jaws are aligned to receive a terminated lead. Forward jaws grip the terminal so that the terminal extends beyond the front end of the forward jaws and the rear jaws grip the wire. In accordance with the method described in this patent, a terminated lead is picked up in the forward jaws. The rear jaws are released and the forward jaws are advanced axially toward a connector housing to partially insert the forward end of the terminal into a connector housing cavity. Thereafter, the rear jaws are closed to maintain the wire lead in this partially inserted position. The front jaws are opened and retracted to their original position adjacent the closed rear jaws. The forward jaws are then reclosed on the wire and the rear jaws reopen. Thereafter, the front jaws are again advanced toward the connector housing thereby moving the terminal further into the connector cavity. In this manner, a terminated lead is inched in discrete steps into the housing cavity by the apparatus. This apparatus also relies on the column strength of the wire to fully insert the terminal into the housing cavity.
Still another automated wire harness fabrication machine is disclosed in U.S. Pat. No. 4,653,160. The apparatus described in this patent is a stand alone, modularized wire processing machine. The machine is capable of feeding wires from a constant supply, cutting them to a specified segment length, and loading them onto a double ended clamped conveyor means. Various wire processing modules are disposed on either side of the conveyor at various positions along its length. As described in the patent, these may include for example, wire stripping modules for stripping end segments of the wire preparatory to crimp termination and crimp terminal attachment presses for securing crimp terminals onto the stripped ends of the wire. Other wire processing modules can be provided along the length of the conveyor including a wire loop forming mechanism and wire labellers.
As described in this latter patent, a connector loading apparatus is provided at the remote end of the lead conveyor. The loading apparatus includes a housing nest which positions a multi-circuit connector housing at an insertion station within this module. A pair of insertion gripper jaws engage a portion of the wire near an end thereof from the conveyor clamps. The insertion gripper jaws are mounted in an arragement which permits the jaws to be moved in any one of three mutually perpendicular axes. In accordance with this apparatus the jaws are indexed in X, Y and Z directions toward the connector housing cavity preparatory to insertion of the wire end into a connector housing cavity. A pair of wire deflector jaws are mounted for movement with the insertion jaws. These jaws are actuable between a closed and an open position. As the insertion jaw assembly advances toward a target cavity, the closed deflector jaws contact the cavity opening of the housing. Thereafter, the deflector jaws are opened to spread or deflect the trailing ends of previously inserted wire leads away from the target cavity opening, and the insertion jaws are moved toward the connector to insert the lead into the cavity.
The insertion apparatus described in the '160 patent has a number of disadvantages. The insertion jaw assembly provides controlled movement in X, Y and Z directions to the insertion jaws to align the jaws with one housing cavity. There is no teaching or suggestion in this patent for indexing the housing to axially align one housing cavity with a gripped wire lead. Because the jaws are moved into alignment, the apparatus is limited in terms of the circuit size of connectors that may be loaded by the apparatus. As stated in the patent, a maximum of four (4) levels or rows of cavities with a maximum of sixteen (16) cavities per level is permitted. The centerline spacing between adjacent cavities must be 5 millimeters or larger. The apparatus may insert leads at random along the same row or can fill one row at a time from a lower row to the top row. The apparatus described in this patent therefore cannot randomly insert leads moving from one column, one row to a remote column and different row. It does not provide for example, for lead insertion in a first cavity followed immediately by insertion in an adjacent cavity directly below the first cavity. The apparatus also relies upon the column strength of the wire lead during insertion. There is no teaching or suggestion in this patent to grip a lead adjacent the rear end of its terminal and to support the wire column and push against the rear of the terminal in order to insert the lead into a housing cavity.
Many of the above mentioned patents describe insertion apparatus which may additionally include push test and pull test arrangements. However, they are all limited in their ability to randomly insert column to column and row to row in multicircuit connector housings and they all to some degree rely upon the column strength of the wire during insertion of the lead which renders their use unsuitable for finer gauge wire leads.